Plastic bag



FIG. 1 is a front perspective view of a plastic bag showing my new design;

FIG. 2 is a rear perspective view thereof;

FIG. 3 is a bottom plan view thereof;

FIG. 4 is a front perspective view of a modified form of my new design;

FIG. 5 is a rear perspective view of the form shown in FIG. 4; and

FIG. 6 is a bottom plan view of the form shown in FIG. 4. 

The ornamental design for a plastic bag, substantially as shown and described. 